Growth and characterization of yttrium oxide thin layers on silicon deposited by yttrium evaporation in atomic oxygen

Abstract

Polycrystalline yttrium oxide films have been grown under high vacuum conditions by evaporation of yttrium in an atomic oxygen plasma. Well-oxidized uniform layers in the thickness interval 30–170 nm were deposited on silicon over a large temperature range (80–800 °C), Film surfaces were very smooth with average surface roughness 1.6 nm for 70 nm films grown at 350 °C. No impurity phases were found by X-ray diffraction even for the highest growth temperatures. The layers exhibited a strong (111) texture for growth temperatures ⩾ 300 °C irrespective of the substrate orientation. High frequency capacitance-voltage measurements on aluminium/yttrium oxide/silicon capacitors showed metal-insulator-semiconductor operation with large hysteresis effects in the depletion region. The calculated values of the relative dielectric constant for the capacitor structures were 14 and 11 for 100 nm thick yttrium oxide films grown at 350 °C and 750 °C, respectively. The breakdown strength of the capacitors was found to be 3.8 MV cm −1.